1. Field of the Invention
The present invention relates to a method for controlling a motor, which is capable of effectively removing noise generated at a hall sensor that measures a position of a rotor in the motor.
2. Description of the Related Art
Generally, for control of a 3-phase brushless motor for motor-driven power steering, it is necessary to accurately calculate position of a rotor in a motor. A stator in such a motor utilizes a magnetic field generated when current flows through a 3-phase coil. On the other hand, the rotor of the motor uses permanent magnets arranged to alternate N and S poles. For continuous rotation of the motor, a continuous rotating magnetic field should be generated in the motor. For generation of such a continuous rotating magnetic field, it is necessary to commutate current flowing through a coil of each phase in an armature at an appropriate point in time. For appropriate commutation, position of the rotor should be accurately recognized. Here, “commutation” refers to reversing the direction of current flowing through the stator coil of the motor, for rotation of the rotor.
For smooth operation of such a motor, position of the rotor should coincide with the point of time when phase current is reversed in direction. Accordingly, a device for detecting position of the rotor is required. Generally, detection of position of the rotor may be achieved using a hall sensor configured to generate a potential difference varying based on a variation in magnetic flux. In another case, a current transformer (CT) is installed for each phase of the stator.
However, even when the above-mentioned hall sensor or CT is used, noise is generated due to friction between elements of the motor. Due to such noise, motor control accuracy may be degraded. Accordingly, various control methods and apparatuses have been proposed. For example, an apparatus capable of achieving an improvement in reliability of basic information for derivation of rotational speed and rotation amount of a motor through removal of noise has been disclosed. However, when a noise signal momentarily enters a Hall sensor configured to transmit and receive only a digital signal, in the above-mentioned conventional case, the Hall sensor may not determine whether the received signal is a noise signal or a normal signal and, as such, speed and position calculation may be erroneously carried out. As a result, speed instability may occur, or motor current control may be erroneously carried out, and, as such, overcurrent may be generated.
The above matters disclosed in this section are merely for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that the matters form the related art already known to a person skilled in the art.